In a multi-tier system, plural servers having different roles exchange messages so as to operate in cooperation and perform a process based on a request from a client. For example, in a system for online banking or an ordering/order-receiving system in Internet shopping, a 3-tier web system is often used which includes a Web server, an application server (hereinafter called AP server) and a database server (hereinafter called DB server). In general, such a system tends to be large-scale and complicated. Therefore, it is difficult to comprehend the operational status of the entire system, and it is not easy to immediately locate a fault if any, for example.
A technology for analyzing the operational status of such a system has been disclosed. In the technology, packets transmitted and received among servers are collected and contents of the collected packets are analyzed, for example. The correspondence between a request message and response message between servers is identified on the basis of identifiers contained in payloads of the collected packets and is output as a protocol log. On the basis of a set of messages selected in accordance with a selection criteria based on the certainty of caller-called relations between processes, a transaction model satisfying a limiting condition for calls between servers is generated. The processing status of the transaction is analyzed on the basis of the protocol log matching the transaction model.
Japanese Laid-open Patent Publication No. 2006-11683 and Japanese Laid-open Patent Publication No. 2007-241805 are examples of related art.
When the payload of a packet transmitted or received between servers is encrypted, it is difficult to associate using the identifiers a specific request message with a specific response message among plural request messages and plural response messages, for example, and it is difficult to create the transaction model and thus to analyze the operational status of the system.